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    <meta charset="UTF-8">
    <title>垂直嵌套盒子塌陷问题</title>
    <style>
        .father {
            width: 400px;
            height: 400px;
            background-color: pink;
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        .son {
            margin-top: 15px;
            width: 200px;
            height: 200px;
            background-color: purple;
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<body>
<div class="collapse">
    <h3>垂直塌陷盒子坍塌问题</h3>
    <p>文字描述：标准流嵌套盒子，给儿子外边距会引起塌陷问题</p>
    <div class="father">
        <div class="son"></div>
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